Sharing experiences can be a benefit.
Someone may tell you how to prevent your victoria sponge from collapsing, which petrol gets the best from your car, how to get stains off a tablecloth, or to avoid getting a sore back lifting things.
So what is so wrong about giving advice on how to enjoy yourself?
And as for being shocked, no one on here provides name and address, or meets face to face, so you are unlikely to look at someone as you queue in the check out, and think. "Doesn't look the type to do that"
And as for being sexually active in old age, if that's what they want, if it gives pleasure, it is very probably good for them.
We all get older each day, so good luck to the OP!
Is there a date / age when going to the gym, or jogging is forbidden?
We don't all like dry wine, but we don't castigate those who do..
Live and let live.
Remember the adage about walking a mile in the other's shoes.